Cellular telephones and other mobile wireless communication devices including PDAs, pagers and wireless email devices are everywhere. Unfortunately, such devices can be mis-used in a manner, for example, to remote control another device in a public place, such as on a bus, train or airplane. There is considerable disagreement on how to balance the conflict between public safety and the convenience of using such mobile communication devices.
The C-Guard LP, by Netline Communications Technologies (NCT) Ltd. of Tel Aviv, Israel, is a low power (LP) jamming device for mobile communications. The LP cell phone jammer unit is intended for blocking all mobile phone types within designated indoor areas. It combines jamming in a radius between 5-80 meters (depending on cellular signal strength at site) and strict compliance with international standards of safety and electromagnetic compatibility. Once the C-Guard cellular jammer is operating, all mobile phones present within the jamming coverage area are blocked, and cellular activity in the immediate surroundings (including incoming and outgoing calls, SMS, pictures sending, etc.) is jammed. Jamming, the act of intentionally directing electromagnetic energy at a communication system to interfere with signal transmission and/or reception, is illegal in many places including the United States of America.
The Defense Advanced Research Projects Agency (DARPA) has developed a jamming system called “Wolfpack” that can be dropped into a conflict zone and can deny use of some communication systems while not interfering with friendly communications.
Furthermore, Cell Block Technologies, Inc. of Fairfax, Va. makes products that provide mobile phone privacy by creating wireless communications-free zones or areas. The Quiet Cell silencing products can detect and control the use of mobile phones within a restricted area e.g. in churches, schools or embassies. Specifically, the product redirects incoming calls to voicemail and blocks outgoing calls.
Iceberg Systems of the United Kingdom makes a system including a security station that may broadcast and inhibiting or disabling signal in a prohibited zone to disable audio or image recording capabilities of a portable device such as a camera phone. The portable device may also be disabled. Such a system and method is described in the published document WO2004089021.
U.S. Pat. No. 6,907,254 to Westfield is directed to a method and apparatus for controlling a quiet zone for wireless units in an IP-based cellular wireless communication system. Entry of a cellular phone device into an area of restricted phone access (“quiet zone”) is detected and an IP message identifying the phone is sent to a central facility. In one embodiment, an IP message is sent to the phone causing it to change behavior, for example turning off the volume on the ringer. Alternatively, the central facility can process an incoming call for a phone that is determined to be in a quiet zone to reduce intrusion in the quiet zone; for example, it can send the call to a phone mailbox or give the caller a busy signal. Such a quiet zone may be in a restaurant or theater.
None of the above described approaches can prevent reception of calls to a mobile device within a relatively small area or zone, with minimal inconvenience to the public by also permitting outgoing transmissions. Accordingly, there is a need for such a system and method.